Abstract:

One or more emitter electrodes of an ion wind fan can be held in tension
by using a slider mechanism in contact with a compression spring. In one
embodiment, an ion wind fan has an isolator with a cavity, and the slider
movably located in the cavity. The fan further includes a spring located
in the cavity, so that the slider compresses the spring when the slider
moves in the cavity. An emitter wire is then attached to the isolator and
to the slider so that the emitter is in tension.

Claims:

1. An ion wind fan comprising:an isolator comprising a cavity;a slider
movably located in the cavity;a spring located in the cavity, so that a
first end of the spring contacts a first wall of the cavity and a second
end of the spring contacts the slider, and wherein the slider compresses
the spring when the slider moves towards the first wall of the cavity;an
emitter wire to be electrically coupled to a high voltage power supply,
wherein the emitter is attached to the isolator and to the slider.

2. The ion wind fan of claim 1, wherein the ion wind fan has a
longitudinal axis and the isolator comprises a first end and a second end
longitudinally opposite to the first end, the emitter wire has a first
end and a second end, and wherein the first and second ends of the
emitter wire are attached to the first end of the isolator.

3. The ion wind fan of claim 2, wherein the cavity is located in the
second end of isolator.

4. The ion wind fan of claim 3, wherein slider comprises wire guide having
curved surface, wherein the emitter wire contacts the wire guide at the
curved surface and is supported by the wire guide.

5. The ion wind fan of claim 1, further comprising a collector electrode
attached to the isolator, wherein the collector electrode is to be
electrically coupled to the high voltage power supply to create a high
potential difference between the emitter wire and the collector
electrode.

6. The ion wind fan of claim 5, wherein creating the high potential
difference between the emitter wire and the collector electrode results
in ion wind in the direction from the emitter wire towards the collector
electrode.

[0002]The embodiments of the present invention are related to ion wind
fans, and in particular to a emitter electrode attachment for an ion wind
fan.

BACKGROUND

[0003]It is well known that heat can be a problem in many electronics
device environments, and that overheating can lead to failure of
components such as integrated circuits (e.g. a central processing unit
(CPU) of a computer) and other electronic components. Most electronics
devices, from LED lighting to computers and entertainment devices,
implements some form of thermal management to remove excess heat.

[0004]Heat sinks are a common passive tool used for thermal management.
Heat sinks use conduction and convection to dissipate heat and thermally
manage the heat-producing component. To increase the heat dissipation of
a heat sink, a conventional rotary fan or blower fan has been used to
move air across the surface of the heat sink, referred to generally as
forced convection. Conventional fans have many disadvantages when used in
consumer electronics products, such as noise, weight, size, and
reliability caused by the failure of moving parts and bearings.

[0005]A solid-state fan using ionic wind to move air addresses the
disadvantages of conventional fans. However, providing an ion wind fan
that meets the requirements of consumer electronics devices presents
numerous challenges not addressed by any currently existing ionic wind
device.

[0006]Three key components of an ion wind fan using a wire-based emitter
electrode (also referred to as the corona electrode) are, a metal
collector which is also the negative electrode or ground electrode, an
emitter which is a metal wire serving as the positive electrode, and a
plastic or other dielectric isolator structure which isolates the
positive and negative electrode and also provides alignment features to
align the collector and one or more emitter electrodes by establishing
the spatial relationships between the electrodes. (The positive and
negative electrode can be switched, i.e. negative corona electrode and
positive or ground collector electrode)

[0007]In some prior art wire corona electrode applications, such as
printers that use wires as the emitter for ink and/or paper charging,
some form of extension spring is used to provide constant tension to the
wire to maintain the performance of the wire as an emitter. Tensioning of
the emitter using a spring can be advantageous because such tensioning
can counter different expansion rates under temperature of the wire
material and the material of the structure which the wire is attached to
(referred to as the isolator), provide leeway for component tolerance
stack up in production and during assembly, and prevent wire stretching
and sagging due to any electromotive forces that the wire may see during
operation of the fan.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a perspective view of an ion wind fan according to one
embodiment of the present invention;

[0009]FIG. 2 is an upstream view of an ion wind fan according to one
embodiment of the present invention;

[0010]FIG. 3 is an upstream plan view of a one-channel ion wind fan
according to one embodiment of the present invention;

[0011]FIG. 4a is an upstream plan view of a two-channel ion wind fan
according to one embodiment of the present invention;

[0012]FIG. 4b is an upstream plan view of a two-channel ion wind fan
according to one embodiment of the present invention; and

[0013]FIG. 5 is an upstream plan view of a three-channel ion wind fan
according to one embodiment of the present invention.

DETAILED DESCRIPTION

[0014]The present invention will now be described in detail with reference
to the drawings, which are provided as illustrative examples of the
invention so as to enable those skilled in the art to practice the
invention. Notably, the figures and examples below are not meant to limit
the scope of the present invention to a single embodiment, but other
embodiments are possible by way of interchange of some or all of the
described or illustrated elements. Moreover, where certain elements of
the present invention can be partially or fully implemented using known
components, only those portions of such known components that are
necessary for an understanding of the present invention will be
described, and detailed descriptions of other portions of such known
components will be omitted so as not to obscure the invention. In the
present specification, an embodiment showing a singular component should
not necessarily be so limited; rather the principles thereof can be
extended to other embodiments including a plurality of the same
component, and vice-versa, unless explicitly stated otherwise herein.
Moreover, applicants do not intend for any term in the specification or
claims to be ascribed an uncommon or special meaning unless explicitly
set forth as such. Further, the present invention encompasses present and
future known equivalents to the known components referred to herein by
way of illustration.

[0015]Ion wind or corona wind generally refers to the gas flow that is
established between two electrodes, one sharp and the other blunt, when a
high voltage is applied between the electrodes. The air is partially
ionized in the region of high electric field near the sharp electrode.
The ions that are attracted to the more distant blunt electrode collide
with neutral (uncharged) molecules en route to the collector electrode
and create a pumping action resulting in air movement. The high voltage
sharp electrode is generally referred to as the emitter electrode or
corona electrode, and the grounded blunt electrode is generally referred
to as the counter electrode, getter electrode, or collector electrode.

[0016]The general concept of ion wind--also sometimes referred to as ionic
wind and corona wind even though these concepts are not entirely
synonymous--has been known for some time. For example, U.S. Pat. No.
4,210,847 to Shannon, et al., dated Jul. 1, 1980, titled "Electric Wind
Generator" describes a corona wind device using a needle as the sharp
corona electrode and a mesh screen as the blunt collector electrode. The
concept of ion wind has been implemented in relatively large-scale air
filtration devices, such as the Sharper Image Ionic Breeze.

Emitter Electrode Attachment

[0017]Wire-based emitter electrodes are typically held in tension in
various corona electrode applications. For example, in printers using
corona electrodes for charging toner particles or paper surfaces, the
corona electrode is held in tension by an extension spring. As another
example, in the "Ionic Breeze" air purifier by Sharper Image, the corona
electrode is held in tension by a large leaf spring to which the corona
attaches. In these application, space is not at the same premium as
inside consumer electronics products, such as laptops, projectors, and
the like, where the space for a cooling fan can be very limited.

[0018]FIGS. 1 and 2 show one example of an ion wind fan in which
embodiments of the present invention can be implemented. In some
configurations, it is advantageous for the tensioning mechanism to be in
the overhead areas because the springs, which are typically metal or
contain metallic material, will not interfere with the corona, and the
tensioning features will not get in the way of airflow. As can be seen
from FIGS. 1 and 2, the overhead area 14 in which tensioning springs can
be designed into is very limited. For some fan designs the overhead area
is only approximately 7 mm by 8 mm, or about 55-60 mm2, and many
other features of the fan, such as electronic connections and fastening
means also take up space in the overhead area. The direction of air flow
is from the wire emitters towards the collector, so in FIG. 2, if there
was a collector attached, the air will flow out of the page during
operation of the ion wind fan.

[0019]On embodiment of the present invention is now described with
reference to FIG. 3. FIG. 3 is a simplified cross-sectional top view of
an ion wind fan, such as the fan shown in FIG. 1, with the collector
electrode omitted for simplicity and ease of understanding. FIG. 3 shows
a single emitter wire electrode 30 held in tension around the frame of an
isolator element 10. The open area under the emitter wire allows air to
flow freely.

[0020]On one side (the right side in FIG. 3), the wire emitter is
terminated and attached to the isolator by a wire termination 32. The
wire termination can be implemented as a plastic heat stake melted around
the wire emitter, a post around which the wire emitter is wrapped, or
using some other wire termination technique. On the opposite side of the
fan (the left side in FIG. 3), the wire emitter is also terminated at a
wire termination 34, but this wire termination 34 is a part of (of
attached to) a spring slider assembly.

[0021]In FIG. 3, the spring slider 36 is represented as a square block
that is situated inside a spring-slider cavity 41. A compression spring
is also situated inside the spring-slider cavity 41, such that the
compression spring 38 contacts the spring slider element 36 on one side
and a wall of the spring-slider cavity 41 on the other side. The cavity
41 can have features that will guide the slider to move in the spring
compression direction smoothly, and to restrict movement in undesired
directions.

[0022]When the compression spring 38 is at fully relaxed, the spring
slider element is situated substantially in the leftmost portion of the
spring-slider cavity 41. As the spring slider moves to the right, sliding
between the sidewalls of the cavity, the compression spring resists such
rightward movement. Therefore, the wire emitter 30 can be held in tension
by the two wire terminations, since one is in a fixed location relative
to the isolator, while the other one is being pushed away from the fixed
termination by the extension of the compression spring under compression.

[0023]Using FIG. 3 as an example, a manufacturing process for tensioning
the electrodes, according to one embodiment, begins before assembly of
the wire emitter with the compression spring being fully relaxed. The
emitter wire is first terminated on the slider block side, leaving the
other side free. During assembly, there are assembly fixtures that will
pull the wire towards the right, compressing the spring, until the spring
is fully or partially compressed. The design of the spring compression
length, spring wire gauge and spring rate is based on the amount of
tensioning that the emitter wire requires and the yield strength of the
emitter wire. While the spring is compressed during the assembly process,
the right end of the wire in FIG. 3 is terminated, leaving the spring to
provide tensioning to the emitter wire in the ion wind fan.

[0024]As mentioned above, such a wire emitter electrode tensioning
technique takes up significantly less space for both attachment and the
spring length, which can be advantageous in a compact ion wind fan
design. Furthermore, such a design allows for using dielectric material
for the spring slider and wire termination on the spring slider, thus
eliminating conductive contact between the metallic spring and the high
voltage emitter electrode. FIG. 3 shown only one emitter electrode
attached according to one embodiment of the present invention, but the
same attachment technique can be duplicated side-by-side. Thus, the
compression spring design is scalable for multiple emitter fan designs.

[0025]Duplicating the compression spring emitter tensioning technique to
accommodate multiple emitters has the disadvantage of using multiple
springs and spring sliders, which all take up limited overhead area
resources. According to another embodiment of the present invention,
multiple wire emitters can be held in tension using a single compression
spring and spring slider mechanism. One such embodiment is now described
with reference to FIGS. 4a and 4b.

[0026]Many aspects of the ion wind fan shown in FIG. 4a are substantially
similar to those shown in and described with reference to FIG. 3.
However, the fan in FIG. 4a has two emitter electrodes that are created
out of a single wire. The wire 40 is held by the isolator 10 by two fixed
wire terminations on one side of the isolator 42a, 42b. On the other
side, there is still a spring slider 42 positioned inside a spring-slider
cavity 41 and adjacent to a compression spring 44. However, instead of
another wire termination, the spring slider element has a slider wire
guide 43 protruding there from.

[0027]The single length of wire 40 is guided around 180 degrees by the
slider wire guide 43. In the embodiment shown in FIG. 4a, the slider wire
guide 43 also determines the spacing between the two emitter electrodes.
In other embodiments, additional guide posts affixed to the isolator may
pull or push the emitter electrodes further apart or closer together than
the width of the slider wire guide.

[0028]In one embodiment, the slider wire guide has a rounded shape where
contacted by the wire, in order to minimize friction forces on the wire
and to evenly distribute the tensioning force of the spring amongst the
two emitter electrodes. In some embodiments it can be advantageous if the
wire guide is made of or coated with a material having a low coefficient
of friction between it and the wire. This can reduce friction and even
out the tensioning of the emitters electrodes, and can prevent damage to
the wire. Alternately, the slider wire guide can be replaced with a
pulley system to reduce friction on the wire.

[0029]FIG. 4b shows the two-emitter configuration described with reference
to FIG. 4a under spring compression. For example, it the coefficient of
thermal expansion (CTE) of the isolator is greater than that of the wire
used for the emitters, then, if the ion wind fan were to be placed in a
hot environment, the isolator would expand physically more than the wire.
In this case, the wire--as looped around the wire guide--would exert
pressure on the spring slider, which would slide forward inside the
spring-slider cavity, thereby compressing the compression spring and
maintaining substantially consistent wire tension in the emitter
electrodes.

[0030]For purposes of illustration, FIG. 4b shows the compression spring
under maximum compression, since the body of the spring slider is
contacting the isolator element in the direction of compression,
preventing further movement of the spring slider. According to other
embodiments, the compression spring may reach maximum compression before
the spring slider would make contact with the isolator.

[0031]Yet another embodiment of the present invention is now described
with reference to FIG. 5. FIG. 5 illustrates how to provide three emitter
electrodes for an ion wind fan using a single wire 50, and a single
compression spring 56 and spring slider 53 assembly. The spring slider
assembly, including the compression spring 56, the spring slider 53
including the slider wire guide, and the spring slider cavity can be
substantially similar to those described above with reference to FIGS. 4a
and 4b. However, instead of the second wire termination on the same side
as the first wire termination 51, another wire guide 52 is placed, and
the wire is guided back towards the side of the isolator having the
spring slider assembly. The wire is then terminated on the same side as
the spring slider assembly using a second wire termination.

[0032]This fixed wire guide can be structurally similar to the slider wire
guide. In one embodiment, it is rounded at least along the edge the
contacts the wire. The fixed wire guide allows for some degree of sliding
of the wire. Therefore, it is advantageous is the coefficient of friction
between the fixed wire guide and the wire is low. This can help keep the
tension of the three wire emitter electrodes substantially constant and
alike. One example material suitable for reducing the coefficient of
friction is Teflon coated plastic, but other such low-friction materials
exist. Alternately, the fixed wire guide can be replaced with a
frictionless or low-friction pulley system to reduce friction on the
wire.

[0033]Theoretically, adding fixed wire guides similar to the one shown in
FIG. 5 would allow for increasing the number of emitter electrodes
provided from a single wire and tensioned using a single compression
spring indefinitely. However, because of frictional losses, using
currently widely available materials and construction techniques,
approximately 3-4 is the maximum number of emitter electrodes that can be
practically provided using a single wire-single spring configuration.

[0034]Other embodiments for providing multiple emitter electrodes
including, for example, replicating the configuration shown in FIGS. 4a
and 4b side by side to provide four emitters. In another embodiment
having four emitters, the configuration shown in FIG. 4 can be provided
twice so that the two spring slider assemblies are on opposite sides of
the ion wind fan. Such an embodiment would use two wires, each used to
create an emitter pair. The overhead area on both sides of the ion wind
fan would have to be large enough to accommodate a spring slider
assembly, such as that described with reference to FIGS. 4a and 4b.

[0035]In yet another embodiment having three emitter electrodes, a
configuration like that described with reference to and shown in FIG. 3
(single electrode--single wire/spring) is disposed between an emitter
pair configured like that shown in FIG. 4a. In other words, the spring
slider assembly on the single wire emitter would be positioned between
the two wire terminations of the single-wire emitter pair. Other similar
electrode configurations are also possible.

[0036]While the example ion wind fan described and pictured above are
shown as having 1-3 emitter electrodes, any number of emitter electrodes
can be used. While most electronics cooling applications using a wire
emitter will have between 1-10 emitter electrodes, the invention is not
limited to any range of emitter electrodes used.

[0037]In the descriptions above, various functional modules are given
descriptive names, such as "ion wind fan power supply." The functionality
of these modules can be implemented in software, firmware, hardware, or a
combination of the above. None of the specific modules or
terms--including "power supply" or "ion wind fan"--imply or describe a
physical enclosure or separation of the module or component from other
system components.

[0038]Furthermore, descriptive names such as "emitter electrode,"
"collector electrode," and "isolator," are merely descriptive and can be
implemented in a variety of ways. For example, the "collector electrode,"
can be implemented as one piece of metallic structure, but it can also be
made of multiple members spaced apart, and connected by wires or other
electrical connections to the same voltage potential, such as ground.

[0039]Similarly, the isolator can be the substantially frame-like
component shown in the Figures, but it can have various shapes. The
electrodes and the isolator are not limited to any particular material;
however, the isolator will generally be made of a dielectric material,
such as plastic, ceramic, and other known dielectrics.